Corrosion of metal surfaces in a fluid has long been a problem for the oil and gas industry. Corrosion in the oil field produces a difficult integrity management challenge for operators and with many fields operating past their design life expectancies, it is extremely important to control corrosion through the use of inhibitors. It is well known that during the production of oil and gas several other corrosive components are present such as brines, organic acids, carbon dioxide, hydrogen sulfide, and microorganisms. Corrosivity to these systems is further magnified by species present in brines, such as organic acids, carbon dioxide (sweet systems), hydrogen sulfide (sour systems), and/or microorganisms, which causes a type of corrosion called microbiologically influenced corrosion or MIC. Other factors that may present problems include high temperatures and pressures, high liquid or gas velocities, solid content, and metal composition. These aggressive constituents can cause severe corrosion to metal pipes, which are often made of low-alloy steels. This problem is even more troublesome in deep-sea operations where replacement of corroded equipment is difficult and costly. Therefore, it is common practice to employ corrosion inhibitors during the production, transportation, storage, and separation of crude oil and natural gas in order to maintain asset integrity, prolong the service life, and protect the environment by reducing/eliminating failures in these systems.
Corrosion inhibitors are usually surface-active compounds that form protective coatings on the surface of metal components, which come in contact with corrosive environments, and thus suppress corrosion. Corrosion inhibitors are compounds, which function to suppress the deterioration of a substance (usually a metal) or its properties caused by reaction with its environment. This occurs as a result of adsorption of the inhibitors to the metal surface, preferentially coating the surface of the metal and forming of a protective film, which modifies the environment at the surface. Common corrosion inhibitors are composed of amines, condensation products of fatty acids with polyamines, e.g. imidazolines or polyamides, and quaternary ammonium compounds. Among the most frequently used corrosion inhibitors in crude oil and natural gas extraction are imidazoline derivatives.
Alternative corrosion inhibitors that can be used alone or in combination with known corrosion inhibitors are being sought by the industry. Further to this point, because of the limited amount and diversity of corrosion inhibitor actives currently available for use in the oil field, newer, high performance, sustainable alternatives are being sought in the industry.